Orbital Polishing with Small Pad for Uniformity
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Solution Overview
Problem
Chemical mechanical polishing (CMP) systems face challenges in achieving uniformity and preventing non-uniform polishing, particularly in addressing localized non-concentric and non-uniform spots on substrates, as traditional rotational polishing methods may not adequately compensate for these issues.
Innovation Solution
A CMP system employing a polishing pad with a contact area smaller than the substrate radius, which undergoes an orbital motion while maintaining a fixed angular orientation relative to the substrate, allowing for precise polishing and reducing the risk of delamination through a pressure-sensitive adhesive coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a traditional rotational polishing method is used, then the polishing process is simple to implement, but it cannot adequately compensate for non-concentric polishing uniformity and localized non-uniform spots
Solution Approach 1:
The polishing pad is made movable with orbital motion capability while maintaining fixed angular orientation. The drive system enables the pad to orbit around the substrate center, transforming the static rotational system into a dynamic orbital system that can adapt to non-concentric defects and achieve uniform polishing across the substrate surface.
Solution Approach 2:
The polishing action is segmented into discrete orbital paths rather than continuous rotation. The small polishing pad (diameter no greater than substrate radius) traverses multiple orbital paths to cover the entire substrate surface, dividing the polishing task into manageable segments that can be systematically controlled to achieve uniformity.
2Manufacturing precision
If a polishing pad with contact area smaller than substrate radius is used, then localized non-uniform spots can be addressed, but the polishing rate may decrease
Solution Approach 1:
The orbital motion ensures continuous contact between the polishing pad and substrate surface without interruption. The pad maintains constant pressure and engagement while orbiting, eliminating idle periods and ensuring every portion of the substrate receives consistent polishing action throughout the orbital cycle.
Solution Approach 2:
The polishing action transitions from simple radial rotation to orbital motion that incorporates tangential movement across the substrate surface. This dimensional change in motion pattern allows the small pad to cover larger effective area while maintaining precise control over contact pressure and polishing uniformity.
3Productivity
If the polishing pad rotates during polishing, then material removal is efficient, but the angular orientation changes cause non-uniform polishing rates
Solution Approach 1:
The system employs orbital motion with fixed angular orientation rather than pure rotation. The polishing pad orbits around the substrate center while maintaining its angular position, creating a dynamic motion pattern that ensures uniform material removal rate across all regions of the substrate without the orientation variations inherent in rotational motion.
Solution Approach 2:
The orbital path creates an asymmetric motion pattern relative to the substrate center, with the pad traveling through different radial positions while maintaining fixed angular orientation. This asymmetric orbital trajectory ensures that all areas of the substrate are exposed to the polishing pad under equivalent conditions, achieving uniformity that symmetric rotation cannot provide.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances polishing uniformity and substrate flatness by compensating for non-concentric polishing uniformity, improving the polishing rate and reducing non-uniformity, while maintaining the polishing pad's orientation to prevent unwanted polishing and improve substrate finish.
Implementation Method 1
a polishing pad with a bottom protrusion that makes contact with the substrate during a polishing operation and a larger radius top portion that is coupled to a polishing pad support with a pressure sensitive adhesive
Data Source
AI summary
A chemical mechanical polishing apparatus includes a plate on which a substrate is received, and a movable polishing pad support and coupled polishing pad which move across the substrate and orbit a local region of the substrate during polishing operation. The load of the pad against the substrate, the revolution rate of the pad, and the size, shape, and composition of the pad, may be varied to control the rate of material removed by the pad.